The food truck business is an emerging industry that depends almost exclusively on free advertising.

"Social media. One hundred percent of our marketing is social media and word of mouth," said the Donny Lines, general manager of NY Slice.

Lines and other food truck operators in Indianapolis have bet the farm on social media. But they have some help from Matt Hanger, who is arguably one of the most important people in the Indianapolis food truck arena.

Of the 46 licensed food truck operators in Indianapolis, only a handful actually know who he is, but they all know his impact. Hanger runs, on his own, the Indy Food Truck Twitter account, an account that has more than 4,100 followers. Hanger keeps tabs on all of the food trucks in Indianapolis, posting their locations and hours of operation.

Matt Kornmeyer is, by Indianapolis food truck standards, an old timer and the operator of "The Scratch Truck."

"I was the ninth truck of the original ten, I think four are gone now," said Kornmeyer.

"When I wrote my business plan, I said for the first year in business, I would not spend anything in advertising and I still have not as of this day," Kornmeyer said.

His specialty is modern comfort food, which dovetails nicely with the entire food truck industry, which is built on social media. Five years ago, Kornmeyer believes that starting a food truck would have been almost impossible without Twitter and Facebook as engines for free advertising.

But the industry still has to fight old-fashioned business realities, about 40 percent of the food truck vendors will or have failed in Indianapolis, which is actually a little better success/failure rate than the traditional brick and mortar restaurants. But Kornmeyer cautions the market is getting tight and may be saturated.